1. Field of the Invention
This invention relates to a sabot separator for a projectile accelerator for launching single, small particles.
2. Description of the Prior Art
The strength of a material against impact can be tested by conducting an impact resistance test in which an object (projectile) is projected onto the material at high velocity.
Acceleration of the particle has conventionally been achieved using a powder gun, gas gun, electrothermal or electromagnetic gun. A method of accelerating a small particle using a powder gun or a gas gun should be avoided, however, because these guns produce contaminating exhaust gases. As a practical matter, therefore, the choice is limited to an electrothermal or electromagnetic accelerator.
As shown in FIG. 4, the electrothermal accelerator has a barrel 1 made of an electrical insulating material, an electrode 2 disposed at the breech of the barrel, an electrode 3 disposed at an intermediate portion thereof, and a circuit 6, which consists of a switch 4 and a high-voltage, large-capacity power supply unit 5, connected between the electrodes 2, 3. An annular evaporation member 7 made of a metal foil with a low vaporization temperature is inserted into the barrel 1 and a projectile 8 is inserted into an intermediate part of the barrel 1. When the switch 4 is closed, the heat generated by the electrical discharge occurring between the electrodes 2, 3 at the breech of the barrel vaporizes the evaporation member 7 and the pressure of the gas generated accelerates the projectile 8 and launches it from the muzzle of the barrel 1.
As shown in FIG. 5(a) and 5(b), the electromagnetic accelerator has a pair of parallel rail electrodes 9, 10 and a pair of insulators 11 that close the spaces between the rails so as to form a barrel 1. A circuit 6 consisting of a switch 4 and a high-voltage, large-capacity power supply unit 5 is connected between the breech ends of the rail electrodes 9, 10, and a projectile 8 is loaded in barrel 1. When the switch 4 is closed, current i flows through an electrically conductive armature 12 attached to the rear of the projectile 8. The current i produces a magnetic field perpendicular to the drawing sheet. The Lorentz force simultaneously produced in the armature 12 accelerates the projectile 8 and launches it from the muzzle of the barrel 1.
In either of the aforesaid accelerators, there is a limit to how small the bore of the barrel 1 can be fabricated. When the projectile 8 to be launched is very small, therefore, it is loaded on a sabot 13 fabricated in a size that is easy to handle (see FIG. 6) and the sabot 13 and the projectile 8 are accelerated together. The muzzle of the barrel 1 is formed with sabot separator 15 with a converging region 14. The sabot 13 is decelerated and stopped by the sabot separator 15, while the projectile 8 separates from the sabot 13 owing to its inertia. Thus only the projectile 8 is launched.
In the prior art sabot separators just described, the high compressive force acting on the sabot 13 when it is decelerated and stopped by impact with the steel sabot separator 15 shatters the peripheral region of the sabot 13 tip. If the velocity of the projectile 8 is high, the sabot 13 may completely disintegrate. In either case, this leads to the problem that fragments 13' fly out of the barrel 1 together with the projectile 8.
This invention was accomplished in the light of the aforesaid problem and has as its object to provide a sabot separator for a projectile accelerator which prevents damage to the sabot and enables complete separation of the sabot and the projectile.